Following the mass extinction of the dinosaurs some 66 million years ago, the Earth underwent a dramatic transformation. This marked the end of the Mesozoic era and the beginning of the Cenozoic era, a new chapter for life on Earth, with a multitude of ecological niches freed up by the disappearance of the dinosaurs. This post-extinction period not only favoured the evolution of new groups of animals and plants, but also allowed for ecological innovations that have shaped ecosystems as we know them today. Following the asteroid impact on the Yucatan Peninsula, the planet suffered a severe environmental disruption. Particles from the impact spread through the atmosphere, partially blocking sunlight and causing a rapid and prolonged cooling known as the impact winter. This event caused massive vegetation die-off and the destruction of the food chain, affecting herbivores first and, by extension, carnivores. The large dinosaurs that once dominated the land became extinct, leaving the way open for other surviving organisms, often smaller and more adaptable, to diversify and fill the niches left vacant. Mammals, previously limited in size and diversity, were among the great beneficiaries of this extinction. Paleontological studies show that some small mammals survived by exploiting niches less dependent on plants directly affected by the lack of light. Thanks to their ability to hide in burrows, hibernate or slow down their metabolism, they were able to escape the most destructive consequences of the post-impact climate. Once conditions stabilized, these small mammals rapidly evolved and diversified their forms. They adapted to the different newly formed ecosystems, some becoming larger to exploit herbivorous niches, while others developed predatory skills or omnivorous diets. This diversification contributed to the emergence of modern orders of mammals, including primates, ungulates and carnivores. During the Paleocene, flowering plants, or angiosperms, also expanded significantly. Following the extinction, fern forests initially dominated the landscape, before being gradually replaced by flowering plants better adapted to post-catastrophe conditions. This shift led to an explosion in biodiversity, as angiosperms provided new food sources and complex habitats for many animals. Coevolution between flowering plants and pollinating insects also intensified, leading to new ecological relationships. Woody plants have allowed the formation of denser forests, and the presence of fruits has provided food resources that have favoured the evolution of new feeding and dispersal strategies for many mammals and birds. Birds, direct descendants of some dinosaurs, also benefited from this new era. With their larger cousins ​​gone, birds were able to colonise diverse habitats and diversify rapidly. Flight-capable species adapted to exploit dense forests and open spaces, while certain lineages evolved to become aquatic birds or large predators. Flight has given birds a unique advantage in finding food and avoiding predators, allowing them to proliferate in every corner of the planet. At the same time, the oceans have also undergone a major transformation. Following the extinction of large marine reptiles such as plesiosaurs and mosasaurs, marine ecosystems evolved to give rise to a new aquatic fauna. Sharks, which survived the extinction, continued to play a role as top predators, while teleost fish (which make up the majority of modern bony fish) thrived in warm, shallow seas. Marine mammals, such as the ancestors of whales, began to evolve to fill ecological roles previously performed by marine reptiles. The rise of diatoms (a type of phytoplankton) also provided a vital food base for new species of planktivorous animals, helping to balance oceanic food chains. As the climate stabilised, the Eocene saw global warming that favoured the proliferation of tropical and subtropical forests, even in polar regions. This channel is an official affiliate of the ORBINEA STUDIO network.